Which probably means I'm right. Mr. Walker, the guy behind Human Transit, just posted a stunningly pictorial version of my argument here, saying that MSA's are a really awful way of measuring transit service. He also specifically cites the Riverside-San Bernardino-Ontario MSA as the prime example of that awfulness, noting not only the vastness of the MSA but the many separate communities that lie within it, "largely experienced by locals as different metros." He cites Riverside/San Berdoo/Ontario and Palm Springs. I'd add in the Victor Valley area, the Barstow area, Needles, and Blythe- all separate communities, all the same MSA.
Sadly, I can't take credit for this post- Mr. Walker is a smart guy, and I'm sure he could come up with the same good idea independently. Still, his posting it pretty much confirms that it's a good idea.